The present invention relates to an aqueous emulsion composition of silicone or, more particularly, to an aqueous emulsion composition of a crosslinkable silicone suitable for use as a surface coating agent in the preparation of a base cloth for automobile air bags as well as to a base cloth for air bags surface-coated with the aqueous emulsion composition of silicone.
A great variety of aqueous emulsion compositions of a crosslinkable silicone, which can give a film of a cured silicone rubber, are known in the prior art and widely employed in the surface treatment of a substrate cloth for preparing a base cloth of air bags for emergency cushioning in automobiles. Some of them are as follows.
(1) Japanese Patent Kokai 56-16553 discloses an anionically stabilized aqueous silicone emulsion having a pH value of 9.0 to 11.5 containing a diorganopolysiloxane having silanolic hydroxyl groups, colloidal silica and an organotin compound or an amine compound.
(2) Japanese Patent Kokai 54-131661 discloses an organopolysiloxane latex composition prepared by the emulsion polymerization of a cyclic organopolysiloxane oligomer and a functional group-containing organo trialkoxy silane compound such as an aminoalkyl trialkoxy silane in combination in an aqueous medium in the presence of a surface active agent which is a sulfonic acid-based compound or a quaternary ammonium salt compound.
(3) U.S. Pat. No. 3,817,894 discloses a silicone latex composition consisting of an organopolysiloxane block copolymer composed of dimethylsiloxane units and monophenyl siloxane units, water, cationic surface active agent, filler and aminosilane compound.
(4) Japanese Patent Kokai 8-85760 discloses an aqueous silicone emulsion composition comprising an organopolysiloxane having silanolic hydroxyl groups, organopolysiloxane having silicon-bonded hydrogen atoms, colloidal silica, organosilane compound having an amide group and carboxyl group in the molecule, organosilane compound having an epoxy group in the molecule and curing catalyst.
(5) Japanese Patent Kokai 9-208826 discloses an aqueous silicone emulsion composition containing an organopolysiloxane having alkenyl groups in the molecule, organopolysiloxane having silicon-bonded hydrogen atoms in the molecule, colloidal silica, reaction product of an aminosilane compound and acid anhydride compound, epoxy-containing organosilane compound and catalytic compound for promoting the hydrosilation reaction between the alkenyl groups and silicon-bonded hydrogen atoms.
(6) Japanese Patent Kokai 9-208900 discloses an aqueous silicone emulsion composition comprising an organohydrogenpolysiloxane end-blocked with hydroxyl groups, surface active agent as an emulsifier, water and curing catalyst.
(7) Japanese Patent Kokai 9-208901, 9-208902 and 9-208903 each disclose an aqueous silicone emulsion composition comprising core-shell particles of a colloidal silica particles and a silicone, curing catalyst, surface active agent as an emulsifier and water.
(8) Japanese Patent Kokai 60-22018 and Japanese Patent No. 2590649 each disclose an aqueous silicone emulsion composition comprising an organopolysiloxane having silanolic hydroxyl groups in the molecule, colloidal silica, reaction product of an aminosilane compound and an acid anhydride compound and curing catalyst.
None of the above described aqueous silicone emulsion compositions in the prior art are, however, quite satisfactory when used as a surface coating agent of a base cloth as a material of air bags in respect of adhesion of the cured silicone films to the substrate cloth and flame retardancy as essential properties to be imparted to the surface-treated base cloth although the surface-treated air bag base cloths proposed by the inventors in Japanese Patent Kokai 8-85405 and 8-208826 have flame retardancy improved to some extent over conventional air bag base cloths.